Adtran T1 ESF CSU ACE 1204025L1 Manual Do Utilizador

T1 ESF CSU ACE User Manual

Chapter 1. Introduction

61204025L1-1B

© 2004 ADTRAN, Inc

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A number of different loopbacks can be invoked locally from the front panel, by T-Watch commands, or 
remotely by using special inband codes (AT&T network loop-up and loop-down codes). Additionally, the 
loopbacks can be remotely controlled by out-of-band commands using the T1 ESF FDL, or from T-Watch 
using a modem connection. A discussion of network loopbacks and DTE interface loopbacks follows.

There are two types of network loopbacks: line loopbacks and payload loopbacks. These are illustrated in 
Figure 1-5.

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Line Loopback - Loops all of the received data back toward the network. The transmitted data is the 
identical line code that was received, including any bipolar violations or framing errors.

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Payload Loopback - Similar to line loopback, except that the framing is extracted from the received data 
and then regenerated for the transmitted data.

Loops all data from the terminal interface (TI) back towards the T1. This loopback may be initiated using 
front panel, EIA-232 control port, or T-Watch commands. The DTE (or external test equipment) must 
provide any test pattern in order to check the DTE interface. See Figure 1-6.